A communication system which communicates via a communications satellite is not easily affected by a disaster such as an earthquake or the like. Thus, various studies are being conducted due to the fact that the above-described communication system is usable even during a disaster.
As an example of this type of communication system, there is a very small aperture terminal (VSAT) system.
In a VSAT system, a planar antenna apparatus which conducts communication control with a communications satellite has, for example, a support placed on an installation surface, first to third movable units rotatable with respect to each other, and an antenna unit supported by the third movable unit. A position of the antenna unit can be adjusted by rotation of the first to third movable units.
It is desirable that the planar antenna apparatus, because of being used outdoors, be stably installed without being inclined under the influence of wind or the like.